In the manufacture of containers comprising combinations of screw-type closures with associated containers, it often becomes necessary or desirable to determine the degree to which the threaded closure complies with applicable torque specifications. For example, the torque with which a threaded closure is applied must be of a certain magnitude to properly seal the container so the closure does not become loose during shipment. Child resistant safety closures may comprise an internally threaded inner cap, threaded directly to the finish of a container, and an outer cap loosely retractable relative to the inner cap. A user must push the outer cap axially upon the inner cap to cause a ratchet mechanism to effect simultaneous engagement between the outer cap and the inner cap to permit removal of the closure from the container.
During the manufacture of products packaged in containers having threaded closures, the closures may be applied by equipment which must be adjusted from time to time to compensate for normal mechanical or component variations which may affect the required application torque. Typically, periodic monitoring of the containers being produced is conducted. During a particular production run, a completed sample container may be tested to determine the degree of torque required to loosen the threaded closure therefrom. If the torque required to remove the closure from the container is outside an acceptable range, the components of the manufacturing process are examined and may be adjusted or replaced. The time required to remove the sample container from a production line for testing may be significant and result in unacceptable production.
There are known prior art devices and methods for affecting quality control torque tests of threaded closures to determine an amount of torque required to remove the closure from the threaded finish of a container. One of the standards of the industry is known as the Owens-Illinois Torque Meter manufactured by Secure Pak, Inc., Maumee, Ohio. There are also bench top torque measuring devices wherein a container to be tested is placed on the device and manually retained to resist any rotational movement during the testing operation. The torque required to remove the associated closure is then measured. To obtain the desired measurements, the containers must be transported to and from the torque measuring device. The torque applied varies from one operator to another. Consequently, torque data produced is often non-uniform and non-reliable in comparison to industry standards. None of the known torque measuring devices measures the linear force, referred to as the downward thrust, required to move an outer cap of a child resistant closure, axially to cause engagement of an associated ratchet mechanism to rotate the inner cap to remove the closure.
It would be desirable to design a handheld device for determining the removal and/or application torque and the downward linear force on a threaded closure required to remove the closure from a container.